Field of the Invention
The present invention relates to a compressor, and more particularly, to a reciprocating compressor, in which suction and compression are made by reciprocation of a piston in a cylinder, and which has improved refrigerant suction and discharge performances.
The compressor in a refrigerator or an air conditioner draws a low temperature and low pressure operating fluid passed through an evaporator, compresses into a high temperature and high pressure fluid in a cylinder and discharges the operating fluid in a high temperature and a high pressure state. A related art reciprocating compressor in a refrigerator and the like will be explained briefly with reference to the attached drawings.
Referring to FIG. 1, the related art reciprocating compressor is provided with a motor part 8 for receiving a current to generate a rotating force, and a compressor part 10 for compressing the refrigerant by the rotating force of the motor part, both of which are enclosed in a case 6 having an upper shell 2 and a lower shell 4. The motor part 8 has a stator 8a for receiving the current to generate an electromagnetic force, and a rotor 8b for generating a rotating force by the electromagnetic force. The compressor part 10 has a crank shaft 12 for rotating with the rotor 8b, a connecting rod 14 for converting a rotating movement of the crank shaft into a linear reciprocating movement, and a piston 18 for compressing refrigerant in a cylinder block 16 by means of the connecting rod. The connecting rod 14 has one end pin coupled to an eccentric piece 12a on top of the crank shaft 12, and the other end pin coupled to the piston 18, for converting the rotating movement of the crank shaft 12 into a linear reciprocating movement. The foregoing compressor operation may be summarized as follows. As the piston 18 makes a linear reciprocating movement in the cylinder block 16 at reception of a rotating movement of the crank shaft 12, the piston 18 converts a low temperature, low pressure refrigerant from the evaporator into a high temperature, high pressure refrigerant through a process of refrigerant suction, compression, and discharge, and forwards to a condenser (not shown). The operation of piston in suction, compression and discharge will be explained, with reference to FIG. 2. FIG. 2 illustrates a suction system and a discharge system of a related art reciprocating compressor, schematically.
Referring to FIG. 2, the crank shaft 12 receives the rotating force from the motor part (see FIG. 1) and rotates the eccentric piece 12a, which rotating force is transmitted to the connecting rod 14 via a sleeve 12b, and the piston 18 coupled to the connecting rod 14 makes a linear reciprocating movement as movement of the piston is restricted in the cylinder block 16. The piston moves from a top dead center to a bottom dead center until a pressure inside of the cylinder 17 is lower than a pressure in a suction muffler 20 when a suction valve 22 is opened to allow the refrigerant to be introduced into the cylinder 17 until the pressure in the cylinder 17 becomes equal to the pressure in the muffler 20. When the piston 18 moves from the bottom dead center to the top dead center, the pressure in the cylinder 17 keeps to build-up to compress the refrigerant until the pressure in the cylinder 17 is higher than an elastic force of a discharge spring (not shown) supporting a discharge valve 24, when the discharge valve 24 is opened, through which a high pressure refrigerant is discharged from the cylinder to a discharge plenum 26. FIG. 3 illustrates a graph showing a result of mathematical modelling of position vs. velocity of the piston 18 fixed by the sleeve 12b and the connecting rod 14, and FIG. 4 illustrates a graph showing position vs. velocity of the piston 18.
Referring to FIG. 3, a position xe2x80x98Pxe2x80x99 of the piston 18 moves along a sinusoidal curve as the piston 18 reciprocates within the cylinder between a top dead center and a bottom dead center, and the velocity of the piston 18 also shows a sinusoidal curve having 90xc2x0 phase difference with the piston position xe2x80x98Pxe2x80x99 as time goes by. FIG. 4 is a graph which facilitate an easy understanding of a relation between position and velocity of the piston, wherefrom it can be known that the piston has a maximum velocity when the piston passes a point M1 and M2 slightly closer to the top dead center from a center of the top dead center and the bottom dead center.
FIG. 5 illustrates a graph showing pressure vs. displacement (volume) of the piston during suction and compression of the piston, in comparison to an ideal condition. As can be known from the drawing, the discharge of refrigerant at a pressure higher than an ideal pressure causes waste of the pressure. As shown in FIGS. 4 and 5, the non-uniform velocity and the excessive velocity and pressure in the vicinity of the top dead center occurred in compression of the piston in the related art compressor causes pressure loss. Contrary to this, the reduced amount of drawn refrigerant in suction coming from a weak suction force caused by a relatively small velocity gradient right before the bottom dead center deteriorates a smooth compression effect and performance of the compressor.
Accordingly, the present invention is directed to a reciprocating compressor that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a reciprocating compressor which can prevent an over pressure loss during refrigerant discharge.
Another object of the present invention is to provide a reciprocating compressor which can improve a compression performance.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the reciprocating compressor includes a connecting rod for converting a rotating movement of a crank shaft into a linear reciprocating movement, a piston for compressing a refrigerant inside of a cylinder block by the connecting rod, and, resonating means having a vibration frequency the same with the piston for applying vibration to a piston movement to give a resonance.
The resonating means includes a supplementary piston for drawing, compressing and discharging the refrigerant in a cylinder in contact with the refrigerant, and a resonator for making the supplementary piston to resonate with the piston.
The resonator is disposed between the piston and the supplementary piston.
Preferably, the resonator is a plate spring, a coil spring, or a pneumatic spring employing an air pressure.
The piston and the supplementary piston include coupling means for preventing break away of the piston and the supplementary piston, and the coupling means includes a coupling tube fitted to the piston, and a coupling rod fitted to the supplementary piston.
The reciprocating compressor further includes a connecting tube for surrounding both the sleeve side part and the piston side part.
The connecting tube and the sleeve side part and the piston side part of the connecting rod include stoppers at both ends, and fore ends thereof, respectively.
The connecting tube has a projection on an inside thereof for limiting a minimum displacement when the sleeve side part and the piston side part come closer.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.